In portable devices, such as, for example, mobile stations, video clips, for example, can be stored on a memory card or similar memory medium. However, according to the prior art, while video capture is taking place, the data is not yet stored on the memory medium in such a way that it could be, for instance, read from it afterwards. This is due to the memory-medium bookkeeping of the prior art and its updating practice in connection with the storing process.
The storing, or rather the updating of the bookkeeping of the memory medium to correspond to the data stored on it, takes place only in connection with the termination of the storing process, i.e. clearly after the actual performance of the video imaging. In the same time, a name or similar identifier for the stored file is created only at this stage. One example of this kind of bookkeeping is the memory medium's space allocation table, i.e. FAT (File Allocation Table) and the directory elementary unit FDE (File Directory Entry), which is generally applied in connection with the FAT. However, there are significant unresolved drawbacks associated with the prior art, relating, for example, to the success of storage and the possibilities to edit stored file.
If there is an unexpected power supply outage during the process of taking a video shot, during which video data is being captured using the camera sensor, then all the data that has been captured up to that point during the shooting session in question, and which has, in principle, already been physically stored on the memory medium, will normally be lost. Even though the data is already stored on the memory card during the video shoot, its location on the storage areas of the memory card has not yet been updated in the bookkeeping of the card, in such a way that it can be used from it later. The data that has been shot and already stored on the memory card thus cannot be restored along with the power supply. An uncontrolled interruption in the power supply can be caused, for example, by the device's battery becoming detached, or also by it running out of power. Such situations are quite common, particularly precisely in portable devices.
In addition, it is difficult to edit video recordings of a large file size, due to the limited storage and memory capacities of memory cards. Once a long video recording has been successfully terminated and the video file has been stored on the memory card, it is quite a large size. For example, a VGA-level recording, in which, for example, 30 frames per second are captured, may result in a file of as much as 1.35 gigabytes. The editing of a file of this size becomes a problem, if, for example, it is wished to remove some part of the clip or cut it, for example, for copying in a second location. The conventional solution to this problem is to make an editing copy of the entire file and leave the original file untouched.
Particularly precisely in portable devices, this may not necessarily always be possible, due to their limited amount of memory and the limited storage capacity of memory cards. This is because the memory card must have a sufficient amount of space to also store the edited shot, in addition to the original shot, which may also be long. If the memory card is already nearly full initially, it will not be possible to edit long shots at all. And even if editing were to be possible within the limits of the memory card's storage capacity, it would be extremely slow, due to the limited speed of the memory card's data-transfer interface.